Clutch device

ABSTRACT

A clutch device includes an input rotor, a rotation support mechanism, a first pressure plate, a second pressure plate, a first clutch disc assembly and a second clutch disc assembly. The input rotor includes a first disc portion and a second disc portion disposed away from the first disc portion at a predetermined space. The rotation support mechanism supports the input rotor for allowing the input rotor to be rotated with respect to a first input shaft and a second input shaft.

CROSS-REFERENCE TO THE RELATED APPLICATIONS

This U.S. national phase application claims priority to Japanese PatentApplication Nos. 2009-296332, 2009-296333, and 2009-296334, all of whichwere filed on Oct. 25, 2009. The entire disclosure of Japanese PatentApplication Nos. 2009-296332, 2009-296333, and 2009-296334 is herebyincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a clutch device for transmitting powerfrom an engine to a transmission.

BACKGROUND ART

Automatic transmissions (ATs) have been known as means for automaticallyshifting gears of vehicles. In recent years, a mainstream type of theATs has a combinational structure of, for instance, a torque converter,a plurality of planet gears and a plurality of clutches. Such a type ofAT does not require an operator to perform clutch operations, normallyrequired in manual transmissions (MTs), in starting moving a vehicle,stopping a vehicle and shifting gears due to a continuous gear shiftingaction by the torque converter and an automatic switching among theplural clutches.

However, torque converters are configured to transmit power throughfluid. Therefore, the power transmission efficiency of the ATs is lowerthan that of the MTs configured to mechanically couple the input sideand the output side directly in transmitting torque. Therefore, the ATshave a drawback of degrading fuel consumption of the vehicles althoughhaving an advantage of reducing operators' effort.

In view of the above, automated manual transmissions (AMTs), structuredbased on the MTs, have been proposed for reliably achieving thetransmission efficiency of the MTs, and simultaneously, eliminating theneed of clutch operations. In the AMTs, the clutch operations of the MTsand the gear-shifting operations of the transmissions are automated.Therefore, the AMTS can reliably achieve a transmission efficiencyequivalent to that of the well-known MTs, and simultaneously, eliminatethe need of clutch operations.

However, the AMTS are configured to decouple the clutches in performinga gear-shifting operation similarly to the MTs and torque transmissionis thereby temporarily prevented. Vehicles travel only by means ofinertia force without accelerating while torque transmission isprevented. Such torque transmission prevention greatly affects theacceleration performance of vehicles and tends to make operators feeluncomfortable.

In view of the above, AMTs employing a twin clutch device have beenproposed for solving the drawback of the torque transmission prevention(see e.g., PTL 1).

Japan Laid-open Patent Application Publication No. JP-A-2002-174262(PTL 1) is an example of the related art.

Japan Laid-open Patent Application Publication No. JP-A-2003-120716 (PTL2) is an example of the related art.

SUMMARY Technical Problems

(1) In the clutch device described in PTL 1, however, a cover memberincluding two flywheels is supported by an engine crankshaft and atransmission. Therefore, rotation of the two flywheels may becomeunstable depending on adjustment accuracy of the axis alignment of theengine and the transmission. Unstable flywheel rotation results inunstable clutch device performance.

It is a first object of the present invention to stabilize clutch deviceperformance.

(2) Further, two clutches can be simultaneously coupled in the clutchdevice described in PTL 1. However, no countermeasure for thisperspective has been proposed so far.

It is a second object of the present invention to provide a clutchdevice for inhibiting two clutches from being simultaneously coupled.

(3) Incidentally, clutch disc assemblies have been known as mechanismsfor transmitting power from an engine to a transmission. This type ofclutch disc assembly includes a friction part, an input member, anoutput member and an elastic member. The elastic member elasticallycouples the input member and the output member in the rotationaldirection. The friction part is fixed to the input member.

The input member includes, for instance, a clutch plate that thefriction part is fixed and a retaining plate fixed to the clutch plate.The elastic member is held by the clutch plate and the retaining platewhile being elastically deformable (see e.g., PTL 2).

However, the clutch disc assembly described in PTL 1 has difficulty inreducing manufacturing cost because compatible use of a component is nottaken into consideration in the clutch disc assembly.

It is a third object of the present invention to provide a clutch discassembly whereby manufacturing cost can be reduced.

A clutch device according to a first aspect of the present invention isa device for transmitting power from an engine to first and second inputshafts of a transmission. The clutch device includes an input rotor, arotary support mechanism, a first pressure plate, a second pressureplate, a first clutch disc assembly and a second clutch disc assembly.The input rotor includes a first disc portion and a second disc portion.The second disc portion is disposed away from the first disc portion ata predetermined space. The rotary support mechanism is disposed betweenthe input rotor and at least either of the first and second inputshafts. The rotary support mechanism supports the input rotor forallowing the input rotor to be rotated with respect to the first andsecond input shafts. The first pressure plate is disposed within theinput rotor. The first pressure plate is disposed unitarily rotatablywith and axially movably with respect to the first disc portion. Thesecond pressure plate is disposed within the input rotor. The secondpressure plate is disposed unitarily rotatably with and axially movablywith respect to the second disc portion. The first clutch disc assemblyis coupled to the first input shaft. The first clutch disc assemblyincludes a first friction part. The first friction part is disposedbetween the first disc portion and the first pressure plate. The secondclutch disc assembly is coupled to the second input shaft. The secondclutch disc assembly includes a second friction part. The secondfriction part is disposed between the second disc portion and the secondpressure plate.

In the clutch device, the rotary support mechanism is disposed betweenthe input rotor and at least either of the first input shaft and thesecond input shaft. Further, the rotary support mechanism supports theinput rotor for allowing it to be rotated with respect to the firstinput shaft and the second input shaft.

Based on the above, the clutch device according to the first aspect ofthe present invention can enhance rotational stability of the inputrotor and stabilize its performance.

A clutch device according to a second aspect of the present invention isa device for transmitting power from an engine to first and second inputshafts of a transmission. The clutch device includes an input rotor, afirst clutch, a second clutch, a first drive mechanism and a seconddrive mechanism. The input rotor receives power transmitted thereto fromthe engine. The first clutch is disposed swichably between a firsttransmitting state of transmitting power from the input rotor to thefirst input shaft and a first blocking state of blocking powertransmission from the input rotor to the first input shaft. The secondclutch is disposed switchably between a second transmitting state oftransmitting power from the input rotor to the second input shaft and asecond blocking state of blocking power transmission from the inputrotor to the second input shaft. The first drive mechanism is amechanism for operating power transmission of the first clutch. Thefirst drive mechanism includes a first drive support member. The firstdrive support member is configured to be axially moved by a first strokein switching the first clutch from the first blocking state to the firsttransmitting state. The second drive mechanism is a mechanism foroperating power transmission of the second clutch. The second drivemechanism includes a second drive support member. The second drivesupport member is configured to be axially moved by a second stroke inswitching the second clutch from the second blocking state to the secondtransmitting state. A drive clearance is configured to be producedaxially between the first drive support member and the second drivesupport member in the first blocking state and the second blockingstate. The drive clearance is less than a sum of the first stroke andthe second stroke.

In the clutch device, the drive clearance is produced axially betweenthe first drive support member and the second drive support member inthe first blocking state and the second blocking state. The driveclearance is less than the sum of the first stroke (SL1) and the secondstroke (SL2). Therefore, the first drive support member and the seconddrive support member interfere with each other even in causing the firstclutch (C1) and the second clutch (C2) to be simultaneously coupled.

Based on the above, the clutch device according to the second aspect ofthe present invention can inhibit the first clutch (C1) and the secondclutch (C2) from being simultaneously coupled.

A clutch disc assembly according to a third aspect of the presentinvention is configured to transmit power from an input rotor to anoutput rotor. The clutch disc assembly includes an annular frictionpart, an input member, an output member and an elastic member. Theannular friction part is disposed slidably with the input rotor. Theinput member receives the friction part coupled thereto. The outputmember is coupled to the output rotor. The elastic member elasticallycouples the input member and the output member in a rotationaldirection. The input member includes a fixation plate, a fixation memberand a holding plate. The fixation plate has at least a fixation hole.The fixation hole (holes) axially penetrates through the fixation plate.The fixation member is inserted into the fixation hole (holes). Thefixation member fixes the friction part to the fixation plate. Theholding plate has at least a spare hole. The spare hole (holes) axiallypenetrates through the holding plate. The holding plate holds theelastic member in an elastically deformable state together with thefixation plate. The spare hole (holes) is disposed in a radial positionsubstantially the same as a radial position of the fixation hole(holes).

In the clutch disc assembly, the spare hole (holes) and the fixationhole (holes) are disposed in substantially the same radial position.Therefore, the same friction part can be fixed to any one of thefixation plate and the holding plate. It is thus possible to compatiblyuse a component.

Based on the above, the clutch disc assembly according to the thirdaspect of the present invention can reduce manufacturing cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a clutch device.

FIG. 2 is a cross-sectional view of the clutch device.

FIG. 3 is a cross-sectional view of the clutch device (the upper half ofFIG. 1).

FIG. 4 is a cross-sectional view of the clutch device (the lower half ofFIG. 1).

FIG. 5 is a cross-sectional view of the clutch device (the upper half ofFIG. 2).

FIG. 6 is a cross-sectional view of the clutch device (the lower half ofFIG. 2).

FIG. 7 is a perspective view of the clutch device.

FIG. 8 is a partial enlarged view of FIG. 7.

FIG. 9 is an exploded perspective view of the clutch device.

FIG. 10 is a partial enlarged view of FIG. 9.

FIG. 11 is a plan view of a diaphragm spring.

FIG. 12 includes a partial plan view (A) of a first pressure plate and apartial plan view (B) of a second pressure plate.

FIG. 13 includes a chart (A) representing the relation between strokeand torque capacity (an exemplary embodiment) and a chart (B)representing the relation between stroke and torque capacity (acomparative example).

FIG. 14 is a partial cross-sectional view of a clutch device (one of theother exemplary embodiments).

FIG. 15 is a partial cross-sectional view of a clutch device (one of theother exemplary embodiments).

FIG. 16 is a partial cross-sectional view of a clutch device (one of theother exemplary embodiments).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

<Entire Structure of Clutch Device>

As illustrated in FIGS. 1 to 9, a clutch device 1 is a device fortransmitting power from an engine to a first input shaft 91 and a secondinput shaft 92 of a transmission. The clutch device 1 includes an inputrotor 10, a first pressure plate 39, a second pressure plate 49, a firstclutch disc assembly 5, a second clutch disc assembly 6 and a drivemechanism 7. A first clutch C1 is formed by the input rotor 10, thefirst pressure plate 39, the first clutch disc assembly 5 and a firstdrive mechanism 7A of the drive mechanism 7. A second clutch C2 isformed by the input rotor 10, the second pressure plate 49, the secondclutch disc assembly 6 and a second drive mechanism 7B of the drivemechanism 7. Both of the first clutch C1 and the second clutch C2 areso-called normal open type clutches. The first clutch C1 is configuredto transmit power at first, third and fifth speed stages, whereas thesecond clutch C2 is configured to transmit power at second and fourthspeed stages.

<Input Rotor 10>

The input rotor 10 is a member receiving power transmitted from theengine. The input rotor 10 is coupled to a crankshaft 99 through aflexible plate 93. The inner peripheral part of the flexible plate 93 isfixed to the crankshaft 99 by means of at least a bolt 99 a, while theouter peripheral part thereof is fixed to the input rotor 10 by means ofat least a bolt 94. A bearing 98 is fixed into an end of the crankshaft99. The tip of the first input shaft 91 is rotatably supported by thebearing 98.

The input rotor 10 mainly includes a first flywheel 3, a second flywheel4, an intermediate plate 38, three first strap plates 82 and threesecond strap plates 85.

(1) First Flywheel 3

The first flywheel 3 includes an annular first disc portion 33, threefirst fixation portions 31, a plurality of first insertion holes 31 d, aplurality of second insertion holes 31 c and a plurality of first ventholes 31 e. The first fixation portions 31 are circular-arc portionsprotruding from the outer peripheral part of the first disc portion 33towards the second flywheel 4. The first fixation portions 31 arealigned at equal pitches in the circumferential direction.

As illustrated in FIGS. 9 and 10, each first fixation portion 31includes first positioning portions 31 a on the tip thereof. The firstpositioning portions 31 a protrude further axially from each firstfixation portion 31. The first positioning portions 31 a come intocontact with the inner peripheral surfaces of second fixation portions38 d of the intermediate plate 38 in the radial direction. Accordingly,the radial position of the intermediate plate 38 is determined withrespect to the first flywheel 3.

The first insertion holes 31 d axially penetrate the first flywheel 3while being disposed correspondingly to first bolts 78 a. The secondinsertion holes 31 c axially penetrate the first flywheel 3 while beingdisposed correspondingly to second bolts 79 a. The first vent holes 31 eaxially penetrate the first flywheel 3 while being disposedsubstantially in the same radial positions as first rivets 53 b.

(2) Second Flywheel 4

The second flywheel 4 includes a second disc portion 43, three secondfixation portions 41, nine protruding portions 42, a plurality of thirdinsertion holes 41 c and a plurality of second vent holes 41 b.

The second disc portion 43 is disposed away from the first disc portion33 in the axial direction. The second fixation portions 41 arecircular-arc portions protruding from the outer peripheral part of thesecond disc portion 43 towards the first flywheel 3. The second fixationportions 41 are aligned at equal pitches in the circumferentialdirection. Three protruding portions 42 are disposed on each secondfixation port ion 41. Three protruding portions 42 of each secondfixation portion 41 are aligned at equal pitches in the circumferentialdirection, while being protruding from the outer peripheral part of thesecond disc portion 43 towards the transmission (i.e., to the oppositeside of the first flywheel 3). Further, the second disc portion 43includes support protruding portions 43 a protruding towards thetransmission. The support protruding portions 43 a come into contactwith a second diaphragm spring 72.

As illustrated in FIGS. 9 and 10, each second fixation portion 41includes second positioning portions 41 a on the tip thereof. The secondpositioning portions 41 a are disposed while being opposed to the firstpositioning portions 31 a in the axial direction. The second positioningportions 41 a protrude further from each second fixation portion 41 inthe axial direction. The second positioning portions 41 a come intocontact with the inner peripheral surfaces of the second fixationportions 38 d of the intermediate plate 38 in the radial direction.Accordingly, the radial position of the intermediate plate 38 isdetermined with respect to the second flywheel 4.

(3) Intermediate Plate 38

The intermediate plate 38 is unitarily rotatable with the first flywheel3 and the second flywheel 4 while being interposed between the firstflywheel 3 and the second flywheel 4. Specifically, the intermediateplate 38 includes an annular intermediate plate main body 38 a, threefirst fixation portions 38 b, the second fixation portions 38 d andprotruding portions 38 e. The intermediate plate main body 38 a isinterposed axially between the first fixation portions 31 and the secondfixation portions 41. The first fixation portions 38 b, the secondfixation portions 38 d and the protruding portions 38 e protruderadially inwards from the intermediate plate main body 38 a. Each firstfixation portion 38 b includes two first holes 38 c. One end of eachfirst strap plate 82 and that of each second strap plate 85 are fixed tothe intermediate plate 38 using one of the first holes 38 c of eachfirst fixation portion 38 b. Each second fixation portion 38 d includesa second hole 38 f.

(4) First Strap Plates 82

The first strap plates 82 elastically couple the first pressure plate 39to the intermediate plate 38 in the axial direction while the firstpressure plate 39 is unitarily rotatable with the intermediate plate 38.For example, each first strap plate 82 is formed by three plateslaminated one above the other. A first end 82 a of each first strapplate 82 is fixed to each first fixation portion 38 b of theintermediate plate 38 by means of a third rivet 81. A second end 82 b ofeach first strap plate 82 is fixed to each first protruding portion 39 aof the first pressure plate 39 by means of a first rivet 83. Each firststrap plate 82 is disposed between two adjacent first fixation portions31 in the circumferential direction.

(5) Second Strap Plates 85

The second strap plates 85 elastically couple the second pressure plate49 to the intermediate plate 38 in the axial direction while the secondpressure plate 49 is unitarily rotatable with the intermediate plate 38.For example, each second strap plate 85 is formed by three plateslaminated one above the other. A first end 85 a of each second strapplate 85 is fixed to each first fixation portion 38 b of theintermediate plate together with the first end 82 a of each first strapplate 82 by means of the third rivet 81. In other words, the thirdrivets 81 fix the first strap plates 82 and the second strap plates 85to the intermediate plate 38. On the other hand, a second end 85 b ofeach second strap plate 85 is fixed to each second protruding portion 49of the second pressure plate 49 by means of a second rivet 84. Eachsecond strap plate 85 is disposed between two adjacent second fixationportions 41 in the circumferential direction.

<Rotation Support Mechanism 11>

A rotation support mechanism 11 is disposed between the first inputshaft 91 and the input rotor 10 while being disposed between the secondinput shaft 92 and the input rotor 10. The rotation support mechanism 11supports the input rotor 10 in a rotatable state with respect to thefirst and second input shafts 91 and 92.

Specifically, the rotation support mechanism 11 includes a first bearing34, a second bearing 44 and a support member 35. The first bearing 34 isdisposed between the first disc portion 33 and the first input shaft 91.The first bearing 34 supports the first disc portion 33 in a rotatablestate with respect to the first input shaft 91. The first bearing 34 isdisposed between the support member 35 and the first disc portion 33.The first bearing 34 is prevented from axially moving with respect tothe first disc portion 33 by a snap ring 34 a.

The second bearing 44 is disposed between the second disc portion 43 andthe second input shaft 92. The second bearing 44 supports the seconddisc portion 43 in a rotatable state with respect to the second inputshaft 92. The second bearing 44 is prevented from moving towards thetransmission by the second input shaft 92.

The support member 35 is attached onto the first input shaft 91 andsupports the first flywheel 3 and the first clutch disc assembly 5. Thesupport member 35 includes a first cylindrical portion 35 b, a secondcylindrical portion 36 a formed on an end of the first cylindricalportion 35 b and a positioning portion 35 c. The first cylindricalportion 35 b is fitted onto a spline of the first input shaft 91. Thefirst cylindrical portion 35 b includes a spline formed on the outerperiphery thereof. The first cylindrical portion 35 b is fitted into afirst hub 51 of the first clutch disc assembly 5. The first cylindricalportion 35 b is prevented from moving towards the engine with respect tothe first input shaft 91 by a ring 36 a and a fixation member 36 b. Theouter diameter of the first cylindrical portion 35 b is substantiallythe same as that of the second input shaft 92. Therefore, it is possibleto use the first hub 51 and a second hub 61 as compatible components.

The second cylindrical portion 35 a is fitted into the inner peripheralside of the first bearing 34. The outer diameter of the secondcylindrical portion 35 a is greater than that of the first cylindricalportion 35 b. The inner diameter of the second cylindrical portion 35 ais greater than that of the first cylindrical portion 35 b. The ring 36a and the fixation member 36 b are disposed on the inner peripheral sideof the second cylindrical portion 35 a.

The positioning portion 35 c is an annular portion protruding radiallyoutwards from the second cylindrical portion 35 a. The positioningportion 35 c is disposed on the engine-side edge of the secondcylindrical portion 35 a. The first bearing 34 is axially positioned bythe second cylindrical portion 35 a.

<First Pressure Plate 39>

The first pressure plate 39 is disposed within the input rotor 10 whilebeing unitarily rotatable with and axially movable with respect to thefirst disc portion 33. Specifically, the first pressure plate 39includes a first main body 39 b having a substantially disc shape, aplurality of first fins 39 c, three first protruding portions 39 a and aplurality of first support portions 39 d.

The first main body 39 b is disposed while being axially opposed to thefirst disc portion 33. As illustrated in FIG. 12(A), the plural firstfins 39 c protrude towards the second disc portion 43 from the firstmain body 39 b while being circumferentially aligned at predeterminedintervals. The first fins 39 c are circumferentially aligned at equalpitches.

The three first protruding portions 39 a protrude radially outwards fromthe first main body 39 b while being circumferentially aligned at equalpitches. The second ends 82 b of the first strap plates 82 are fixed tothe first protruding portions 39 a. The first support portions 39 dprotrude radially outwards from the first main body 39 b while beingcircumferentially aligned at equal pitches. A first drive support member78 of the first drive mechanism 7A is coupled to the first supportportions 39 d.

<Second Pressure Plate 49>

The second pressure plate 49 is disposed within the input rotor 10 whilebeing unitarily rotatable with and axially movable with respect to thesecond disc portion 43. Specifically, the second pressure plate 49includes a second main body 49 b having a substantially disc shape, aplurality of second fins 49 c, three second protruding portions 49 a anda plurality of second support portions 49 d.

The second main body 49 b is disposed while being axially opposed to thesecond disc portion 43. As illustrated in FIG. 12(B), the plural secondfins 49 c protrude towards the first disc portion 33 from the secondmain body 49 b while being circumferentially aligned at predeterminedintervals. The second fins 49 c are circumferentially aligned at equalpitches. Each first fin 39 c is partially disposed between adjacent twosecond fins 49 c in the circumferential direction. The first fins 39 cand the second fins 49 c are alternately disposed in the circumferentialdirection.

The three second protruding portions 49 a protrude radially outwardsfrom the second main body 49 b while being circumferentially aligned atequal pitches. The second ends 85 b of the second strap plates 85 arefixed to the second protruding portions 49 a. The second supportportions 49 d protrude radially outwards from the second disc portion 43while being circumferentially aligned at equal pitches. A second drivesupport member 79 of the second drive mechanism 7B is coupled to thesecond support portions 49 d.

<First Clutch Disc Assembly 5>

The first clutch disc assembly 5 is an assembly for transmitting powerfrom the input rotor 10 to the first input shaft 91. The first clutchdisc assembly 5 is coupled to the first input shaft 91 through thesupport member 35. The first clutch disc assembly 5 includes a firstfriction part 57, a first input member 52, the first hub 51 and aplurality of first springs 55.

The first friction part 57 includes a pair of annular-shaped firstfriction facings 57 a and an annular-shaped first core plate 57 b towhich the paired first friction facings 57 a are fixed. The firstfriction part 57 (more specifically, the first friction facings 57 a) isdisposed axially between the first disc portion 33 and the firstpressure plate 39. The first friction part 57 is disposed slidably withthe input rotor 10 and the first pressure plate 39.

The first input member 52 is a member to which power is transmitted fromthe first friction part 57. The first input member 52 is coupled to thefirst friction part 57. The first input member 52 includes a firstclutch plate 53, a first retaining plate 54 and the first rivets 53 b.The first clutch plate 53 includes a plurality of first fixation holes53 a axially penetrating therethrough. The first fixation holes 53 a areformed in the outer periphery of the first clutch plate 53. The firstrivets 53 b are inserted into the first fixation holes 53 a for fixingthe first friction part 57 to the first clutch plate 53. The firstretaining plate 54 holds the first springs 55 in an elasticallydeformable state together with the first clutch plate 53. The firstretaining plate 54 includes a plurality of first spare holes 54 aaxially penetrating therethrough. The first spare holes 54 a aredisposed in substantially the same radial positions as the firstfixation holes 53 a. The inner diameter of each first spare hole 54 a issubstantially the same as that of each first fixation hole 53 a.

The first spare holes 54 a are disposed while being axially opposed tothe first fixation holes 53 a. The first spare holes 54 a are formed inthe outer periphery of the first retaining plate 54.

The first hub 51 is coupled to the first input shaft 91 through thesupport member 35. The first springs 55 are supported by the first inputmember 52 while being elastically deformable. The first springs 55elastically couple the first input member 52 and the first hub 51 in therotational direction.

<Second Clutch Disc Assembly 6>

The second clutch disc assembly 6 is an assembly for transmitting powerfrom the input rotor 10 to the second input shaft 92 and is coupled tothe second input shaft 92. The second clutch disc assembly 6 includes asecond friction part 67, a second input member 62, the second hub 61 anda plurality of second springs 65.

The second friction part 67 includes a pair of annular-shaped secondfriction facings 67 a and an annular-shaped second core plate 67 b towhich the paired second friction facings 67 are fixed. The secondfriction part 67 (more specifically, the second friction facings 67 a)is disposed axially between the second disc portion 43 and the secondpressure plate 49. The second friction part 67 is disposed slidably withthe input rotor 10 and the second pressure plate 49.

The second input member 62 is a member to which power is transmittedfrom the second friction part 67. The second input member 62 is coupledto the second friction part 67. The second input member 62 includes asecond clutch plate 63, a second retaining plate 64 and second rivets 63b. The second clutch plate 63 includes a plurality of second fixationholes 63 a axially penetrating therethrough. The second fixation holes63 a are formed in the outer periphery of the second clutch plate 63.The second rivets 63 b are inserted into the second fixation holes 63 afor fixing the second friction part 67 to the second clutch plate 63.The second retaining plate 64 holds the second springs 65 in anelastically deformable state together with the second clutch plate 63.The second retaining plate 64 includes a plurality of second spare holes64 a axially penetrating therethrough. The second spare holes 64 a aredisposed in substantially the same radial positions as the secondfixation holes 63 a. The inner diameter of each second spare hole 64 ais substantially the same as that of each second fixation hole 63 a. Thesecond spare holes 64 a are disposed while being axially opposed to thesecond fixation holes 63 a. The second spare holes 64 a are formed inthe outer periphery of the second retaining plate 64.

The second hub 61 is coupled to the second input shaft 92. The secondsprings 65 are supported by the second input member 62 while beingelastically deformable. The second springs 65 elastically couple thesecond input member 62 and the second hub 61 in the rotationaldirection.

<Drive Mechanism 7>

(1) First Drive Mechanism 7A

The first drive mechanism 7A is a mechanism for operating powertransmission of the first clutch C1. The first drive mechanism 7A isconfigured to transmit axial pressing force to the first pressure plate39. The first drive mechanism 7A includes the first drive support member78, the first bolts 78 a and a first diaphragm spring 71. The firstdrive support member 78 is supported by the input rotor 10. The firstbolts 78 a couple the first drive support member 78 to the firstpressure plate 39 in a detachable state while being screwed into thefirst drive support member 78 and the first support portions 39 d of thefirst pressure plate 39. The first diaphragm spring 71 is configured totransmit driving force to the first drive support member 78 for movingthe first drive support member 78 towards the first disc portion 33 withrespect to the input rotor 10.

The first diaphragm spring 71 includes a first coupling portion 71 ahaving an annular shape, a plurality of first intermediate portions 71 dand a plurality of first lever portions 71 b. The first intermediateportions 71 d extend radially inwards from the first coupling portion 71a while being circumferentially aligned at predetermined intervals. Thefirst lever portions 71 b extend radially further from the firstintermediate portions 71 d while being circumferentially aligned atpredetermined intervals.

A maximum dimension H11 of each first lever portion 71 b in thecircumferential direction is greater than a maximum dimension H12 ofeach first intermediate portion 71 d in the circumferential direction. Aradial dimension H14 of the first coupling portion 71 a is same as orless than a radial dimension H13 from each first lever portion 71 b tothe first coupling portion 71 a (corresponding to a radial dimension ofeach first intermediate portion 71 d). The first coupling portion 71 aaxially comes into contact with the first drive support member 78.

The first drive support member 78 includes a second support plate 73having an annular shape and six first tubular members 78 b. The secondsupport plate 73 includes a second main body 73 c having an annularshape, a protruding portion 73 a protruding towards the transmission,six second drive protruding portions 73 b protruding radially outwardsfrom the second main body 73 c and three second guide portions 73 d. Thefirst tubular members 78 b are fixed to the second drive protrudingportions 73 b on a one-to-one basis. Each second drive protrudingportion 73 b is disposed between adjacent two of the protruding portions42. Each second guide portion 73 d is disposed between adjacent twoprotruding portions 42 that are disposed on one ends of adjacent twosecond fixation portions 41. The second support plate 73 is supported bythe second fixation portions 41 while being unitarily rotatable with andaxially movable with respect to the second flywheel 4.

(2) Second Drive Mechanism 7B

The second drive mechanism 7B is a mechanism for operating powertransmission of the second clutch C2. The second drive mechanism 7B isconfigured to transmit axial pressing force to the second pressure plate49. The second drive mechanism 7B includes the second drive supportmember 79, the second bolts 79 a and the second diaphragm spring 72.

The second drive support member 79 is supported by the input rotor 10.The second bolts 79 a couple the second drive support member 79 to thesecond pressure plate 49 in a detachable state while being screwed intothe second drive support member 79. The second diaphragm spring 72 isconfigured to transmit driving force to the second drive support member79 for moving the second drive support member 79 towards the second discportion 43 with respect to the input rotor 10.

The second diaphragm spring 72 includes a second coupling portion 72 ahaving an annular shape, a plurality of second intermediate portions 72d and a plurality of second lever portions 72 b. The second intermediateportions 72 d extend radially inwards from the second coupling portion72 a while being circumferentially aligned at predetermined intervals.The second lever portions 72 b extend radially further from the secondintermediate portions 72 d while being circumferentially aligned atpredetermined intervals.

A maximum dimension H21 of each second lever portion 72 b in thecircumferential direction is greater than a maximum dimension H22 ofeach second intermediate portion 72 d in the circumferential direction.A radial dimension H24 of the second coupling portion 72 a is same as orless than a radial dimension H23 from each second lever portion 72 b tothe second coupling portion 72 a (corresponding to a radial dimension ofeach second intermediate portion 72 d). The second coupling portion 72 aaxially comes into contact with the second drive support member 79.

The second drive support member 79 includes a third support plate 74having an annular shape and six second tubular members 79 b. The thirdsupport plate 74 includes a third main body 74 c having an annularshape, a third protruding portion 74 a protruding towards the engine,six third drive protruding portions 74 b protruded radially outwardsfrom the third main body 74 c, and three third guide portions 74 d. Thesecond tubular members 79 b are fixed to the third drive protrudingportions 74 b on a one-to-one basis. Each third drive protruding portion74 b is disposed between adjacent two of the protruding portions 42.Each third guide portion 74 d is disposed between adjacent twoprotruding portions 42 that are disposed on one ends of adjacent twosecond fixation portions 41. The third support plate 74 is supported bythe second fixation portions 41 while being unitarily rotatable with andaxially movable with respect to the second flywheel 4.

<Relation between Stroke and Transmission Torque>

Relations between stroke and transmission torque of the first clutch C1and those of the second clutch C2 will be hereinafter explained usingFIGS. 13(A) and 13(B). FIG. 13(A) corresponds to the clutch device 1,whereas FIG. 13(B) corresponds to a clutch device as a comparativeexample. In FIG. 13(A), the horizontal axis represents strokes of thefirst and second pressure plates 39 and 49 while the vertical axisrepresents torque capacities of the first and second clutches C1 and C2.Further, the right end of the horizontal axis is set as the origin ofthe stroke of the first pressure plate 39 (i.e., a position where thedriving force of the drive mechanism 7 does not act). On the other hand,the left end of the horizontal axis is set as the origin of the secondpressure plate 49 (i.e., a position where the driving force of the drivemechanism 7 does not act).

With the aforementioned configuration, the first clutch C1 is hereindisposed while being switchable between a first transmitting state S11and a first blocking state S12. In the first transmitting state S11,power is transmitted from the input rotor 10 to the first input shaft91. In the first blocking state S12, power is blocked from beingtransmitted from the input rotor 10 to the first input shaft 91.Specifically, the first drive support member 78 (or the first pressureplate 39) is disposed while being configured to be axially moved by afirst stroke SL1 when the first clutch C1 is switched from the firstblocking state S12 to the first transmitting state S11. Therefore, thedisplacement of the first pressure plate 39 from the first transmittingstate S11 to the first blocking state S12 corresponds to the firststroke SL1. The maximum torque capacity represented in FIG. 13(A) is atorque capacity where the first clutch C1 is completely coupled andindicates a torque capacity in the first stroke SL1.

Further, with the aforementioned configuration, the second clutch C2 isdisposed while being switchable between a second transmitting state S21and a second blocking state S22. In the second transmitting state S21,power is transmitted from the input rotor 10 to the second input shaft92. In the second blocking state S22, power is blocked from beingtransmitted from the input rotor 10 to the second input shaft 92. Thesecond drive support member 79 (or the second pressure plate 49) isdisposed while being configured to be axially moved by a second strokeSL2 when the second clutch C2 is switched from the second blocking stateS22 to the second transmitting state S21. Therefore, the displacement ofthe second pressure plate 49 from the second transmitting state S21 tothe second blocking state S22 corresponds to the second stroke SL2. Themaximum torque capacity represented in FIG. 13(A) is a torque capacitywhere the second clutch C2 is completely coupled and indicates a torquecapacity in the second stroke SL2.

As illustrated in FIGS. 3 and 4, in the clutch device 1, a driveclearance H is produced axially between the first drive support member78 and the second drive support member 79 in the first blocking stateS12 and the second blocking state S22. More specifically, the driveclearance H is produced axially between the second support plate 73 andthe third support plate 74 in the first blocking state S12 and thesecond blocking state S22. The drive clearance H is set to be less thanthe sum of the first stroke SL1 and the second stroke SL2. Accordingly,the first clutch C1 and the second clutch C2 are inhibited from beingsimultaneously coupled.

Further, from the perspective of the relation between torque capacities,the torque capacity of the first clutch C1 in the first transmittingstate S11 is a first maximum torque capacity T1max. The torque capacityof the second clutch C2 in the second transmitting state S21 is a secondmaximum torque capacity T2max. In the second transmitting state S21 ofthe second clutch C2, the torque capacity of the first clutch C1 is afirst minimum torque capacity T1min when the first drive support member78 and the second drive support member 79 come into contact with eachother. In the first transmitting state S11 of the first clutch C1, thetransmission torque of the second clutch C2 is a second minimum torquecapacity T2min when the first drive support member 78 and the seconddrive support member 79 come into contact with each other.

Where an intermediate contact state is defined as a state that the firstdrive support member 78 and the second drive support member 79 come intocontact with each other in an intermediate position of the driveclearance H, a sum Tm of the transmission torque of the first clutch C1and that of the second clutch C2 in the intermediate contact state isless than or equal to a sum T12max of the first maximum torque capacityT1max and the second minimum torque capacity T2min. Likewise, the sum Tmof the transmission torque of the second clutch C2 and that of the firstclutch C1 in the intermediate contact state is less than or equal to asum T21max of the second maximum torque capacity T2max and the firstminimum torque capacity T1min.

Further, the drive clearance H is set so that a greater one (T_total) ofthe maximum torque capacity T12max and the maximum torque capacityT21max can be less than a torque (T_lock) at which wheels are locked(slip) against the road.

Thus, adjustment of the drive clearance H can prevent both of the firstand second clutches C1 and C2 from being simultaneously coupled, andfurther, prevent locking or slipping of wheels.

It should be noted in the clutch device as a comparative example thatthe sum Tm of the transmission torque of the second clutch C2 and thatof the first clutch C1 in the intermediate contact state becomes greaterthan a lock torque (T_lock) as represented in FIG. 13(B). Therefore, thefirst and second clutches C1 and C2 are simultaneously coupled and thismay cause locking (slipping) of wheels

<Actions of Clutch Device 1>

Actions of the clutch device 1 will be explained. In the statesillustrated in FIGS. 1 to 6, pressing force is not applied to the firstand second clutches C1 and C2 by the drive mechanism 7 while powertransmission is not executed in the first and second clutches C1 and C2.In the state, the first pressure plate 39 is held by the first strapplates 82 in the axial positions illustrated in FIGS. 1 to 6, while thesecond pressure plate 49 is held by the second strap plates 85 in theaxial positions illustrated in FIGS. 1 to 6. When power is transmittedfrom the engine to the input rotor 10, the input rotor 10, the firstpressure plate 39, the second pressure plate 49 and the drive mechanism7 are unitarily rotated. The first input shaft 91 supports the firstbearing 34 through the support member 35, while the first bearing 34supports the first flywheel 3 in a rotatable state. On the other hand,the second input shaft 92 supports the second bearing 44, while thesecond bearing 44 supports the second flywheel 4 in a rotatable state.Therefore, the input rotor 10 is stably rotated.

For example, when the vehicle starts moving at the first speed, thefirst input shaft 91 side of the transmission is switched into the firstspeed and a first drive bearing 76 of the first drive mechanism 7A ispressed towards the engine by means of a first actuator (not illustratedin the figures). As a result, the first diaphragm spring 71 iselastically deformed while being pressed on a first protrusion 75 a as afulcrum. The second support plate 73 is thereby pressed towards theengine. When the second support plate 73 is pressed through the firstdiaphragm spring 71, the first drive support member 78 and the firstpressure plate 39 are moved towards the engine. As a result, the firstfriction part 57 of the first clutch disc assembly 5 is interposed andheld between the first pressure plate 39 and the first flywheel 3 (morespecifically, the first disc portion 33), and power is transmitted tothe first input shaft 91 through the first clutch disc assembly 5. Withthe actions, the vehicle starts moving at the first speed.

In shifting the speed stage from the first speed to the second speed,the second input shaft 92 side of the transmission is switched into thesecond speed. The second clutch C2 is switched into the coupled statesubstantially simultaneously with decoupling of the first clutch C1while the transmission is set to be in the second speed. Specifically,driving force acting on the first drive mechanism 7A is released and thefirst drive bearing 76 is returned to the transmission side. As aresult, the first diaphragm spring 71 is returned to the statesillustrated in FIGS. 1 to 4, and power transmission through the firstclutch C1 is released.

On the other hand, a second drive bearing 77 of the second drivemechanism 7B is pressed towards the engine by means of a second actuator(not illustrated in the figures). As a result, the second diaphragmspring 72 is elastically deformed while being pressed on the supportprotruding portion 43 a as a fulcrum, and the third support plate 74 ispulled towards the transmission. When the third support plate 74 ispressed by the second diaphragm spring 72, the second drive supportmember 79 and the second pressure plate 49 are moved towards thetransmission. As a result, the second friction part 67 of the secondclutch disc assembly 6 is interposed and held between the secondpressure plate 49 and the second flywheel 4 (more specifically, thesecond disc portion 43), and power is transmitted to the second inputshaft 92 through the second clutch disc assembly 6. With the actions,the speed stage is switched from the first speed to the second speed.

<Features>

The aforementioned features of the clutch device 1 will be hereinaftercomprehensively described.

(A)

(1) As illustrated in FIGS. 1 to 4, the clutch device 1 includes therotation support mechanism 11 that supports the input rotor 10 withrespect to the first and second input shafts 91 and 92 in a rotatablestate. The rotation support mechanism 11 is disposed between the firstinput shaft 91 and the input rotor 10, while being disposed between thesecond input shaft 92 and the input rotor 10.

Specifically, the rotation support mechanism 11 includes the first andsecond bearings 34 and 44. The first bearing 34 is disposed between thefirst disc portion 33 of the first flywheel 3 and the first input shaft91. The second bearing 44 is disposed between the second disc portion 43of the second flywheel 4 and the second input shaft 92.

With the employment of such structure, it is possible to enhance therotational stability of the input rotor 10 and stabilize the performanceof the clutch device 1.

(2) As illustrated in FIGS. 1 to 4, the rotation support mechanism 11includes the support member 35 mounted onto the first input shaft 91.The first bearing 34 is disposed between the support member 35 and thefirst disc portion 33. In this case, the specification of the firstbearing 34 can be easily changed by replacing the support member 35 withanother member with a diameter different from that of the support member35. It is thereby possible to provide the clutch device 1 compatiblewith various types of transmissions.

Further, the support member 35 supports the first clutch disc assembly5, and the outer diameter of the second input shaft 92 is substantiallythe same as that of the first cylindrical portion 35 b of the supportmember 35. Therefore, it is possible to compatibly use components of thefirst clutch disc assembly 5 and the second clutch disc assembly 6(i.e., the first hub 51 and the second hub 61).

(3) As illustrated in FIGS. 7 and 8, the input rotor 10 includes theplural third rivets 81 for fixing the first strap plates 82 and thesecond strap plates 85 to the intermediate plate 38. Therefore, it ispossible to compatibly use a component and the number of components canbe thereby reduced. In other words, it is possible to reducemanufacturing cost with the aforementioned structure.

(4) As illustrated in FIG. 12(A), the first pressure plate 39 includesthe plural first fins 39 c. The first fins 39 c protrude towards thesecond disc portion 43 from the first main body 39 b while beingcircumferentially aligned at predetermined intervals. On the other hand,as illustrated in FIG. 12(B), the second pressure plate 49 includes thesecond fins 49 c. The second fins 49 c protrude towards the first discportion 33 from the second main body 49 b while being circumferentiallyaligned at predetermined intervals.

Thus, it is possible to increase a heat dissipation area by providingthe first fins 39 c for cooling in the first pressure plate 39 andproviding the second fins 49 c for cooling in the second pressure plate49. It is thereby possible to enhance durability of the first and secondpressure plates 39 and 49.

Further, each first fin 39 c is at least partially disposedcircumferentially between adjacent two of the second fins 49 c.Therefore, the air flowing between the first fins 39 c and the secondfins 49 c reliably flows through the vicinity of the surface of thefirst pressure plate 39 and the vicinity of the surface of the secondpressure plate 49. It is thereby possible to further enhance coolingeffect for the first and second pressure plates 39 and 49.

(5) As illustrated in FIGS. 1, 3 and 4, the first drive mechanism 7Aincludes the first drive support member 78, the first bolts 78 a and thefirst diaphragm spring 71. The first drive support member 78 issupported by the input rotor 10. The first bolts 78 a are screwed intothe first pressure plate 39 while detachably coupling the first drivesupport member 78 to the first pressure plate 39. The first diaphragmspring 71 transmits driving force to the first drive support member 78so that the first drive support member 78 can be moved towards the firstdisc portion 33 with respect to the input rotor 10.

The first drive support member 78 is detachably attached to the firstpressure plate 39 by means of the first bolts 78 a. Therefore,workability is enhanced in a maintenance work.

Similarly in the case of the second drive mechanism 7B, the second drivesupport member 79 is detachably attached to the second pressure plate 49by means of the second bolts 79 a. Therefore, workability is enhanced ina maintenance work.

Further, the first flywheel 3 of the input rotor 10 includes the firstinsertion holes 31 d. The first insertion holes 31 d axially penetratethrough the first flywheel 3 while being disposed in correspondingpositions to the first bolts 78 a. Therefore, an attachment/detachmentwork of the first bolts 78 a can be easily executed.

Yet further, when the first friction part 57 is abraded, the position ofthe first pressure plate 39 can be adjusted in accordance with abrasionof the first friction part 57 by changing the trunk lengths of the firstbolts 78 a.

Similarly in the case of the second drive mechanism 7B, the secondflywheel 4 includes the second insertion holes 31 c. The secondinsertion holes 31 c axially penetrate through the second flywheel 4while being disposed in corresponding positions to the second bolts 79a. Therefore, an attachment/detachment work of the second bolts 79 a canbe easily executed.

(6) As illustrated in FIG. 11, the first diaphragm spring 71 includesthe annular first coupling portion 71 a, the plural first intermediateportions 71 d and the plural first lever portions 71 b. The firstintermediate portions 71 d extend radially inwards from the firstcoupling portion 71 a while being circumferentially aligned atpredetermined intervals. The first lever portions 71 b extend radiallyfurther from the first intermediate portions 71 d while beingcircumferentially aligned at predetermined intervals. The maximumdimension H11 of each first lever portion 71 b in the circumferentialdirection is greater than the maximum dimension H12 of each firstintermediate portion 71 d in the circumferential direction. The radialdimension H14 of the first coupling portion 71 a is less than the radialdimension H13 from each first lever portion 71 b to the first couplingportion 71 a (corresponding to the radial dimension of each firstintermediate portion 71 d). Therefore, it is possible to remarkablyreduce the stiffness of the first diaphragm spring 71 and regulate thestiffness of the first diaphragm spring 71 to be suitable for the clutchdevice 1 of a normal open type.

It should be noted that the feature of the first diaphragm spring 71 isalso true to the second diaphragm spring 72.

(B)

(1) As illustrated in FIGS. 3 to 6, the drive clearance H is producedaxially between the first drive support member 78 and the second drivesupport member 79 in the first blocking state S12 and the secondblocking state S22. The drive clearance H is less than the sum of thefirst stroke SL1 and the second stroke SL2. Therefore, it is possible toprevent the first clutch C1 and the second clutch C2 from beingsimultaneously coupled.

(2) As illustrated in FIG. 13, the transmission torque of the firstclutch C1 in the first transmitting state S11 is the first maximumtorque capacity T1max. In the first transmitting state S11 of the firstclutch C1, the transmission torque of the second clutch C2 is the secondminimum torque capacity T2min when the first drive support member 78 andthe second drive support member 79 come into contact with each other.The state that the first drive support member 78 and the second drivesupport member 79 come into contact with each other in the intermediateposition of the drive clearance H is the intermediate contact state. Thesum Tm of the transmission torque of the first clutch C1 and that of thesecond clutch C2 in the intermediate contact state is less than or equalto the sum T12max of the first maximum torque capacity T1max and thesecond minimum torque capacity T2min. Therefore, it is possible to morereliably prevent the first clutch C1 and the second clutch C2 from beingsimultaneously coupled.

Further, as illustrated in FIG. 13, the transmission torque of thesecond clutch C2 in the second transmitting state S21 is the secondmaximum torque capacity T2max. In the second transmitting state S21 ofthe second clutch C2, the transmission torque of the first clutch C1 isthe first minimum torque capacity T1min when the first drive supportmember 78 and the second drive support member 79 come into contact witheach other. The sum Tm of the transmission torque of the second clutchC2 and that of the first clutch C1 in the intermediate contact state isless than or equal to the sum T21max of the second maximum torquecapacity T2max and the first minimum torque capacity T1min. Therefore,it is possible to more reliably prevent the first clutch C1 and thesecond clutch C2 from being simultaneously coupled.

(C)

(1) As illustrated in FIGS. 3 to 6, the first input member 52 includesthe first clutch plate 53, the first rivet/rivets 53 b and the firstretaining plate 54. The first clutch plate 53 has at least one firstfixation hole 53 a axially penetrating therethrough. The firstrivet/rivets 53 b is/are inserted into the first fixation hole/holes 53a for fixing the first friction part 57 to the first clutch plate 53.The first retaining plate 54 has at least one first spare hole 54 aaxially penetrating therethrough. The first retaining plate 54 holds thefirst springs 55 in an elastically deformable state together with thefirst clutch plate 53. The first spare hole/holes 54 a is/are disposedin substantially the same radial position/positions as the firstfixation hole/holes 53 a. With the structure, the same first frictionpart 57 can be fixed to any one of the first clutch plate 53 and thefirst retaining plate 54. Thus, compatible use of a component can beachieved. The feature is also true to the second clutch disc assembly 6.

It should be herein noted that the device on which the first and secondclutch disc assemblies 5 and 6 are mounted is not limited to the clutchdevice 1 and may be a single clutch device, for instance.

(2) Each first spare hole 54 a has an inner diameter substantially thesame as that of each first fixation hole 53 a. The first spare holes 54a are disposed in positions axially opposed to the first fixation holes53 a. Further, the first fixation holes 53 a are formed in the outerperiphery of the first clutch plate 53. The first spare holes 54 a areformed in the outer periphery of the first retaining plate 54.Therefore, compatible use of a component can be further easily achieved.

<Other Exemplary Embodiments>

The present invention is not limited to the aforementioned exemplaryembodiment. A variety of changes and modifications can be herein madewithout departing from the scope of the present invention. It should benoted that the same reference numerals are assigned to elements havingsubstantially the same functions as those in the aforementionedexemplary embodiment and detailed explanation thereof will behereinafter omitted.

(1) In the aforementioned exemplary embodiment, the damper mechanism isprovided for each of the first and second clutch disc assemblies 5 and6. However, a damper mechanism may be disposed between the engine andthe input rotor 10. For example, a clutch device 101 illustrated in FIG.14 includes a first clutch disc assembly 105, a second clutch discassembly 106 and a damper mechanism 120 disposed between the engine andthe input rotor 10. The damper mechanism 120 elastically couples thecrankshaft 99 of the engine to the input rotor 10. Further, no dampermechanism is disposed in each of the first and second clutch discassemblies 105 and 106. Specifically, the first clutch disc assembly 105includes the first friction part 57 and the first hub 51 but does notinclude the first springs 55. Further, the second clutch disc assembly106 includes the second friction part 67 and the second hub 61 but doesnot include the second springs 65.

On the other hand, the damper mechanism 120 includes a first input plate124, a second input plate 123, a plurality of springs 126, an outputplate 125, an intermediate member 122, a flexible plate 121 and a sealmechanism 127. The first input plate 124 is fixed to the crankshaft 99by means of the bolt 99 a. The second input plate 123 is fixed to thefirst input plate 124. The springs 126 are elastically deformablyretained by the first input plate 124 and the second input plate 123.Further, the actuation space, accommodating the springs 126, is filledwith lubricating oil and is sealed by the seal mechanism 127. Thesprings 126 elastically couple the first input plate 124 and the outputplate 125 in the rotational direction. The intermediate member 122 isfixed to the inner periphery of the output plate 125 together with theflexible plate 121. The flexible plate 121 is fixed to the firstflywheel 3 by means of bolts 129.

Even the clutch device 101 can achieve the same advantageous effects asthose achieved by the clutch device of the aforementioned exemplaryembodiment.

(2) In the aforementioned exemplary embodiment, the first pressure plate39 and the second pressure plate 49 are coupled to the input rotor 10using the first strap plates 82 and the second strap plates 85. However,another structure may be used instead. For example, in a clutch device201 illustrated in FIG. 15, an input rotor 210 includes a shaft 299, afirst support spring 297 and a second support spring 298. The shaft 299is attached to the first flywheel 3 and the second flywheel 4.Accordingly, the first pressure plate 39 and the second pressure plate49 are respectively supported by the shaft 299 while being unitarilyrotatable with and axially movable with respect to the first flywheel 3and the second flywheel 4. The first support spring 297 is elasticallydeformably supported by the shaft 299, while being disposed between thefirst flywheel 3 and the first pressure plate 39. The second supportspring 298 is elastically deformably supported by the shaft 299, whilebeing disposed between the second flywheel 4 and the second pressureplate 49.

Further, the first pressure plate 39 includes a first rubber member 295(an exemplary third elastic member) having a tubular shape. The secondpressure plate 49 includes a second rubber member 296 (an exemplaryfourth elastic member) having a tubular shape. Specifically, asillustrated in FIG. 15, the first rubber member 295 elastically couplesthe shaft 299 to the first pressure plate 39 while being disposedbetween the shaft 299 and the first pressure plate 39. The second rubbermember 296 elastically couples the shaft 299 to the second pressureplate 49 while being disposed between the shaft 299 and the secondpressure plate 49. The first and second rubber members 295 and 296 canprevent the first and second pressure plates 39 and 49 from hitting withthe shaft 299 and from producing sounds.

Even the clutch device 201 can achieve the same advantageous effects asthose achieved by the clutch device in the aforementioned exemplaryembodiment.

(3) In the aforementioned exemplary embodiment, the rotation supportmechanism 11 includes both of the first and second bearings 34 and 44.However, the rotation support mechanism 11 may include only either ofthe bearings.

For example, a clutch device 301 can be assumed as illustrated in FIG.16. The clutch device 301 includes an input rotor 310, the firstpressure plate 39, the second pressure plate 49, a bearing 334, thedrive mechanism 7 and a damper mechanism (not illustrated in thefigure). Similarly to the aforementioned damper mechanism 120, amechanism for elastically coupling the crankshaft 99 and the input rotor310 can be herein assumed as the damper mechanism.

The input rotor 310 includes a first flywheel 303, a second flywheel 304and a cover 302. The first flywheel 303 is rotatably supported by thebearing 334. The bearing 334 is fitted onto the outer peripheral side ofthe support member 35.

The first flywheel 303 includes a first disc portion 333 and an innerperiphery fixation portion 339. The first disc portion 333 is configuredto slide along the first friction part 57 of the first clutch discassembly 5. The inner periphery fixation portion 339 is fixed onto theouter periphery of the bearing 334 by means of a snap ring 334 a. Thefirst disc portion 333 protrudes entirely towards the engine than theinner periphery fixation portion 339 is, while being disposed closer tothe engine than the bearing 334 is. The second flywheel 304 is fixed tothe first flywheel 303. The second flywheel 304 includes a flangedportion 341, a tubular portion 342 and a second disc portion 343. Theflanged portion 341 is fixed to the outer periphery of the firstflywheel 303. The tubular portion 342 is disposed on the outerperipheral side of the first clutch disc assembly 5 and the secondclutch disc assembly 6. The second disc portion 343 is configured toslide along the second friction part 67 of the second clutch discassembly 6. The cover 302 supports the drive mechanism 7 while beingfixed to the second flywheel 304.

In the clutch device 301, the first disc portion 333 is disposed closerto the engine than the bearing 334 is. Therefore, the center of gravityof the entire input rotor 310 gets closer to the bearing 334. Therefore,the input rotor 310 can be supported only by the bearing 334.

(4) In the aforementioned exemplary embodiment, the first positioningportions 31 a and the second positioning portions 41 a are disposed inthe inner peripheral side of the intermediate plate 38. However, anysuitable structure can be employed as long as the intermediate plate 38can be thereby positioned in the radial direction. For example, thefirst positioning portions 31 a and the second positioning portions 41 amay be disposed on the outer peripheral side of the intermediate plate38, or alternatively, may be disposed on both of the inner and outerperipheral sides of the intermediate plate 38.

The invention claimed is:
 1. A clutch device for transmitting power froman engine to first and second input shafts of a transmission, the clutchdevice comprising: an input rotor including a first disc portion and asecond disc portion, the second disc portion disposed away from thefirst disc portion at a predetermined space; a rotary support mechanismdisposed between the input rotor and at least one of the first andsecond input shafts, the rotary support mechanism supporting the inputrotor to be rotated with respect to the first and second input shafts,the rotary support mechanism including a first bearing disposed betweenthe first disc portion and a support member mounted on an outerperipheral portion of the first input shaft, the first bearing beingdisposed between the support member and the first disc portion in aradial direction, and the first bearing supporting the first discportion to be rotated with respect to the first input shaft; a firstpressure plate disposed within the input rotor, the first pressure platedisposed unitarily rotatably and axially movably with respect to thefirst disc portion; a second pressure plate disposed within the inputrotor, the second pressure plate disposed unitarily rotatably andaxially movably with respect to the second disc portion; a first clutchdisc assembly coupled to the first input shaft, the first clutch discassembly including a first friction part, which is disposed between thefirst disc portion and the first pressure plate, the first clutch discassembly being supported by the support member; and a second clutch discassembly coupled to the second input shaft, the second clutch discassembly including a second friction part, which is disposed between thesecond disc portion and the second pressure plate.
 2. The clutch devicerecited in claim 1, wherein the rotary support mechanism includes asecond bearing, which is disposed between the second disc portion andthe second input shaft, and the second bearing supports the second discportion to be rotated with respect to the second input shaft.
 3. Theclutch device recited in claim 1, wherein the input rotor includes afirst rotor and a second rotor, the first rotor includes the first discportion, and the second rotor includes the second disc portion and fixedto the first rotor.
 4. The clutch device recited in claim 3, wherein theinput rotor includes an intermediate plate interposed between the firstrotor and the second rotor, a first coupling member couples the firstpressure plate to the intermediate plate axially elastically andunitarily rotatably therewith, a second coupling member couples thesecond pressure plate to the intermediate plate axially elastically andunitarily rotatably therewith, and the intermediate plate is disposedunitarily rotatably with the first rotor and the second rotor.
 5. Theclutch device recited in claim 4, wherein the input rotor includes afixation member fixing the first coupling member and the second couplingmember to the intermediate plate.
 6. The clutch device recited in 4,wherein the first rotor includes a first positioning portion, which isdisposed on at least one of inner and outer peripheral sides of theintermediate plate, and the first positioning portion radially comesinto contact with the intermediate plate.
 7. The clutch device recitedin claim 4, wherein the second rotor includes a second positioningportion, which is disposed on at least either of inner and outerperipheral sides of the intermediate plate, and the second positioningportion radially comes into contact with the intermediate plate.
 8. Theclutch device recited in claim 4, wherein the first rotor includes afirst positioning portion, which is disposed on at least one of innerand outer peripheral sides of the intermediate plate, the firstpositioning portion radially comes into contact with the intermediateplate, the second rotor includes a second positioning portion, which thesecond positioning portion is disposed on at least one of inner andouter peripheral sides of the intermediate plate, the second positioningportion radially comes into contact with the intermediate plate, and thesecond positioning portion is disposed so as to be axially opposed tothe first positioning portion.
 9. The clutch device recited in claim 3,wherein the input rotor includes a shaft mounted on the first rotor andthe second rotor, the shaft supports the first pressure plate and thesecond pressure plate unitarily rotatably and axially movably withrespect to the first rotor and the second rotor, respectively, theclutch device includes a first elastic support member and a secondelastic support member, the first elastic support member is elasticallydeformably supported by the shaft, the first elastic support member isdisposed between the first rotor and the first pressure plate, thesecond elastic support member is elastically deformably supported by theshaft, and the second elastic support member is disposed between thesecond rotor and the second pressure plate.
 10. The clutch devicerecited in claim 9, wherein the input rotor includes a third elasticmember inserted between the shaft and the first pressure plate, and afourth elastic member inserted between the shaft and the second pressureplate, the third elastic member elastically couples the shaft to thefirst pressure plate, and the fourth elastic member elastically couplesthe shaft to the second pressure plate.
 11. The clutch device recited inclaim 1, wherein the first pressure plate includes a first main bodyhaving a substantially disc shape and a plurality of first finsprotruding from the first main body towards the second disc portion, andthe first fins are circumferentially aligned at predetermined intervals.12. The clutch device recited in claim 1, wherein the second pressureplate includes a second main body having a substantially disc shape anda plurality of second fins protruding from the second main body towardsthe first disc portion, and the second fins are circumferentiallyaligned at predetermined intervals.
 13. The clutch device recited inclaim 1, wherein the first pressure plate includes a first main bodyhaving a substantially disc shape and a plurality of first finsprotruding from the first main body towards the second disc portion, thefirst fins are circumferentially aligned at predetermined intervals, thesecond pressure plate includes a second main body having a substantiallydisc shape and a plurality of second fins protruding from the secondmain body towards the first disc portion, the second fins arecircumferentially aligned at predetermined intervals, and each of thefirst fins is at least partially disposed circumferentially between twoof the second fins being next to each other.
 14. The clutch devicerecited in one of claims 1, further comprising a first drive mechanismconfigured to transmit axial pressing force to the first pressure plate,wherein the first drive mechanism includes a first drive support membersupported by the input rotor, a first screw member screwed into thefirst drive support member, and a first drive member configured totransmit driving force to the first drive support member to be movedtowards the first disc portion with respect to the input rotor, and thefirst screw member detachably couples the first drive support member tothe first pressure plate.
 15. The clutch device recited in claim 14,wherein the input rotor includes a first insertion hole, which axiallypenetrates through the input rotor, and the first insertion hole isdisposed in a position corresponding to a position of the first screwmember.
 16. The clutch device recited in claim 14, wherein the firstdrive member includes a first coupling portion having an annular shape,a plurality of first intermediate portions extending radially inwardsfrom the first coupling portion, and a plurality of first lever portionsradially extending further from the first intermediate portions, amaximum circumferential dimension of the first lever portion is greaterthan a maximum circumferential dimension of the first intermediateportion, a radial dimension of the first coupling portion is same as orless than a radial dimension from the first lever portion to the firstcoupling portion, the first intermediate portions circumferentiallyaligned at predetermined intervals, the first lever portionscircumferentially aligned at predetermined intervals.
 17. The clutchdevice recited in claim 16, wherein the first coupling portion axiallycomes into contact with the first drive support member.
 18. The clutchdevice recited in claim 1, further comprising a second drive mechanismconfigured to transmit axial pressing force to the second pressureplate, wherein the second drive mechanism includes a second drivesupport member supported by the input rotor and a second screw memberscrewed into the second drive support member, the second screw memberdetachably couples the second drive support member to the secondpressure plate, and a second drive member is configured to transmitdriving force to the second drive support member to be moved towards thesecond disc portion with respect to the input rotor.
 19. The clutchdevice recited in claim 18, wherein the input rotor includes a secondinsertion hole, the second insertion hole axially penetrates through theinput rotor, and the second insertion hole is disposed in a positioncorresponding to a position of the second screw member.
 20. The clutchdevice recited in claim 18, wherein the second drive member includes asecond coupling portion having an annular shape, a plurality of secondintermediate portions extending radially inwards from the secondcoupling portion, and a plurality of second lever portions radiallyextending further from the second intermediate portions, a maximumcircumferential dimension of the second lever portion is greater than amaximum circumferential dimension of the second intermediate portion, aradial dimension of the second coupling portion is same as or less thana radial dimension from the second lever portion to the second couplingportion, the second intermediate portions circumferentially aligned atpredetermined intervals, and the second lever portions circumferentiallyaligned at predetermined intervals.
 21. The clutch device recited inclaims 20, wherein the first coupling portion axially comes into contactwith the first drive support member.
 22. The clutch device recited inclaim 1, further comprising a damper mechanism disposed between theengine and the input rotor, the damper mechanism elastically coupling acrankshaft of the engine to the input rotor.